Various inorganic materials are now widely employed for industrial use in consideration of both property of the material and requirement of the use. A silicic ceramic material, for example, is excellent in mechanical strength, chemical resistance, and thermal stability. A silicic material such as silicone oxide, and titanium oxide additionally has excellent optical properties.
Since the inorganic material is hard and brittle, it is generally difficult to mold and to process the inorganic material. The inorganic material is also poor in adhesiveness with an organic material, and therefore the use is restricted.
On the other hand, the organic polymer is flexible and is easily processed. However, their hardness and thermal stability are largely inferior to those of the inorganic material.
Therefore, there is great demand for the material which is able to complement to each other in their properties, and is able to make the use of the respective advantages thereof.
In respect of the problem, for improving physical properties of a plastic material such as surface hardness, gloss, soil resistance, hardness, heat resistance, weather resistance, and chemical resistance, studies of organic-inorganic hybrid polymer material has been made in which an inorganic element such as Si, Ti, and Zr is incorporated.
In the process for preparing the organic-inorganic hybrid polymer material, it is known that an organic monomer or an organic polymer, and an inorganic frame containing compound such as alkylsiloxane are radically copolymerized, or an inorganic functional group such as alkoxy silane is bound to an organic polymer as a pendent group, and then the organic polymer is crosslinked.
Japanese Patent Kokai Publication No. 57642/1988, 103486/1991, and J. Appl. Polym. Sci., vol. 35, pages 2039 to 2051, 1988, for example disclose the process for preparing an organic-inorganic hybrid polymer material in which an organic monomer or an organic polymer is radically polymerized by using an alkyl siloxane-containing compound as an initiator. However, it is even difficult to introduce an alkyl siloxane moiety to the both end of the organic monomer or the organic polymer, and it is impossible to introduce a siloxane frame uniformly into the structure of the resulting polymer, by the abovedescribed process in which an alkyl siloxane-containing compound is used as an initiator. At present, the synthesis of the alkyl siloxane-containing compound also requires complicated procedures.
Macromolecules, vol. 24, No. 6, page 1431, 1991, describes the method for preparing a siloxane-containing polymer by the anionic polymerization method. However, in order to obtain the intended polymer material, the reaction conditions must be carefully controlled because the reactivity and the physical property of the employed material are different from each other.
Additionally, the anionic polymerization is high in cost, and it is not practical to conduct the above described process under the industrial scale.
Japanese Patent Kokai Publication No. 43679/1993, and 86188/1993 describe the process for preparing an organic-inorganic hybrid polymer material in which a vinyl polymer and a silicone compound having a silane group (Si--H group) are subjected to the hydrosilylation reaction, and then the resultant are crosslinked by the sol-gel method.
Japanese Patent Kokai Publication No. 104710/1996, and 104711/1996 describe the process for preparing an organic-inorganic hybrid polymer material in which a vinyl monomer is radically polymerized using an alkoxysilyl group-end capped azoic initiator, and the resulting alkoxysilyl group-end capped vinyl polymer is hydrolyzed and polycondensed. There is described here polystyrene, polyvinyl chloride, an acrylic resin as the vinyl polymer.
The vinyl polymers however are poor in heat resistance and mechanical strength, and are not suitable for employing as a high-performance plastic material, particularly as a structural material and a hard coating material.
Macromolecules, vol. 25, page 4309, 1992, discloses the process for preparing an organic-inorganic hybrid polymer material in which an alkoxysilyl group is bonded to a main chain of a polyalkylene oxide polymer, and the resultant is hydrolyzed and polycondensed. As the main chain of the organic-inorganic hybrid polymer material, Macromol. Chem. Macromol. Symp., vol. 42/43, page 303, 1991, discloses a polyoxazoline polymer, J. Inorg. Organomet. Polym., vol. 5, No. 4, pages 343 to 375, 1995, discloses a polyamine polymer, and J. Appl. Polym. Sci., vol. 58, page 1263, 1995, discloses a cellulose polymer.
However, all the polymers described above as the main chain of the organic-inorganic hybrid polymer material, are hydrophilic. The hydrophilic polymers are hygroscopic, poor in water resistance, and are not suitable for employing as a plastic molded material, a sealing material, a coating raw material, a structural material, a hard coating material, and the like.
On the other hand, hydrophobic polymers, particularly engineering plastics are excellent in heat resistance, mechanical strength, and water resistance. Hydrophobic polymers are widely demanded and employed as an industrial plastic material. The development of an organic-inorganic hybrid polymer material using a hydrophobic polymer is therefore generally required.
However, hybridization by using a hydrophobic polymer is generally difficult because a hydrophobic polymer is not soluble or hardly soluble into an alcoholic solvent which is usually employed as a solvent for the sol-gel reaction, and the number of reactive functional group in a hydrophobic polymer is generally poor. Therefore, there is no reference which describes the organic-inorganic hybrid polymer material using the hydrophobic polymer.
The hydrophobic polymer generally has a small number of functional group therein as described above. The hydrophobic polymer often has only two functional groups at the terminal ends. As a result, the content of an inorganic moiety of the resulting organic-inorganic hybrid polymer material is up to few % by weight. Such a minor content of the inorganic moiety is not sufficient to improve physical strength of the organic-inorganic hybrid polymer material such as heat resistance, hardness, and the like.
In the process of the sol-gel method, a porous gel is formed by subjecting a raw material such as metal alkoxide to hydrolysis and polycondensation. The porous gel has recently been employed as a catalyst. It is otherwise used as glass or ceramics after that the pores thereof is stopped by sintering at high temperature (e.g., Sumio SAKUKA et al., "Science of sol-gel method").
Glass is well-known as a material having excellent gas-barrier ability, and is commonly used as a container for sealing. However, the glass has a drawback of heavy and easy to break.
On the other hand, polycarbonate is a material which has relatively poor gas-barrier ability among the engineering plastics. Therefore, the polycarbonate heretofore has not been commonly used as a container for sealing even though it has excellent impact resistance and transparency.
That is, if the glass and the polycarbonate are combined and the drawbacks thereof are complemented and the advantages thereof are exploited, the resulting material will have excellent properties, and it must be used as an alternate of a glass container or a glass material.